[1] Univ Alabama Birmingham, Heersink Sch Med, Grad Med Educ, Birmingham, AL 35294 USA
[2] Univ Alabama Birmingham, Div Pulm Allergy & Crit Care Med, Birmingham, AL 35294 USA
[3] Univ Alabama Birmingham, Gregory Fleming Cyst Fibrosis Res Ctr, Birmingham, AL 35294 USA
[4] Univ Alabama Birmingham, Dept Phys Therapy, Birmingham, AL 35294 USA